How to report FX gains on dividends?

Over the years, I have accumulated a small amount of USD from individual stock dividends, held in my Rakuten Securities account.

Recently, I transferred those USD to JPY and I am wondering how I should proceed to report FX gains in e-tax. (e.g. acquired "dividend 1/2/3" in 2013 at a 140/142/144 USD/JPY rate but sold in 2014 at 150 USD/JPY)

Also, considering I have dozens of entries for acquired dividends, I am wondering if there is a simple way to do it instead of manually inputting each dividend payment transaction.

Thanks in advance for the help!